This invention relates generally to expandable retractable portable structures. More particularly, the invention relates to an actuating system and hinged roof design for expanding and retracting a portable structure.
The structure of the present invention can be used in trailers, motorized vehicles and also without a chassis. The structure without a chassis can be moved by cranes and flatbed trucks. The structure can be efficiently transported by boat or airplane in its retracted configuration, with or without a chassis.
The prior art includes the expandable-retractable portable structure of U.S. Pat. No. 5,265,394 dated Nov. 30, 1993. That patent teaches a structure which utilizes a relatively complex cable and winch system for expanding and retracting the structure. The design shown in that patent poses the inherent risk that, if the cable broke or became disconnected, the movable portion would fall, potentially injuring or killing workmen and damaging the structure. It is, therefore, desirable that a reliable and inherently safe actuation mechanism be provided for such expandable and retractable structures.
According to the present invention, a hydraulic, pneumatic, or gear driven actuation system is provided to move the structure between its expanded and retracted positions. The present invention utilizes an actuator carried either beneath or on top of the floor of the stationary portion of the structure. The actuating system is inherently safer, simpler and more rugged than the cable and winch system of U.S. Pat. No. 5,265,394.
A primary object of the present invention is to provide a safe, simple and rugged actuation mechanism for an expandable retractable portable structure.
A further object of the invention is to provide an expandable retractable structure having a hinged roof and which opens and closes in a single pivoting motion.
Another object of the invention is to provide an expandable and retractable portable structure having a plurality of rollers for carrying the weight of the roof of the movable portion.
Another object of the invention is to provide an improved roof seal joint which facilitates opening, closing and sealing the roof structure readily.
Other objects and advantages will become apparent from the following description and the drawings wherein: